diff --git a/cypress/integration/rendering/sequencediagram.spec.js b/cypress/integration/rendering/sequencediagram.spec.js
index 6bedd233e..1122a3009 100644
--- a/cypress/integration/rendering/sequencediagram.spec.js
+++ b/cypress/integration/rendering/sequencediagram.spec.js
@@ -452,6 +452,42 @@ context('Sequence diagram', () => {
         {}
       );
     });
+    it('should render rect around and inside criticals', () => {
+      imgSnapshotTest(
+        `
+        sequenceDiagram
+          A ->> B: 1
+          rect rgb(204, 0, 102)
+            critical yes
+              C ->> C: 1
+            option no
+              rect rgb(0, 204, 204)
+                C ->> C: 0
+              end
+            end
+          end
+          B ->> A: Return
+      `,
+        {}
+      );
+    });
+    it('should render rect around and inside breaks', () => {
+      imgSnapshotTest(
+        `
+        sequenceDiagram
+          A ->> B: 1
+          rect rgb(204, 0, 102)
+            break yes
+              rect rgb(0, 204, 204)
+                C ->> C: 0
+              end
+            end
+          end
+          B ->> A: Return
+      `,
+        {}
+      );
+    });
     it('should render autonumber when configured with such', () => {
       imgSnapshotTest(
         `
diff --git a/docs/sequenceDiagram.md b/docs/sequenceDiagram.md
index bb925db28..286009d4d 100644
--- a/docs/sequenceDiagram.md
+++ b/docs/sequenceDiagram.md
@@ -230,6 +230,70 @@ sequenceDiagram
     end
 ```
 
+## Critical Region
+
+It is possible to show actions that must happen automatically with conditional handling of circumstances.
+
+This is done by the notation
+
+```
+critical [Action that must be performed]
+... statements ...
+option [Circumstance A]
+... statements ...
+option [Circumstance B]
+... statements ...
+end
+```
+
+See the example below:
+
+```mermaid-example
+sequenceDiagram
+    critical Establish a connection to the DB
+        Service-->DB: connect
+    option Network timeout
+        Service-->Service: Log error
+    option Credentials rejected
+        Service-->Service: Log different error
+    end
+```
+
+It is also possible to have no options at all
+
+```mermaid-example
+sequenceDiagram
+    critical Establish a connection to the DB
+        Service-->DB: connect
+    end
+```
+
+This critical block can also be nested, equivalently to the `par` statement as seen above.
+
+## Break
+
+It is possible to indicate a stop of the sequence within the flow (usually used to model exceptions).
+
+This is done by the notation
+
+```
+break [something happened]
+... statements ...
+end
+```
+
+See the example below:
+
+```mermaid-example
+sequenceDiagram
+    Consumer-->API: Book something
+    API-->BookingService: Start booking process
+    break when the booking process fails
+        API-->Consumer: show failure
+    end
+    API-->BillingService: Start billing process
+```
+
 ## Background Highlighting
 
 It is possible to highlight flows by providing colored background rects. This is done by the notation
@@ -300,8 +364,8 @@ It is possible to get a sequence number attached to each arrow in a sequence dia
 
 ```html
     <script>
-      mermaid.initialize({ sequence: { showSequenceNumbers: true }, });
-    </script>
+    mermaid.initialize({ sequence: { showSequenceNumbers: true }, });
+</script>
 ```
 
 It can also be be turned on via the diagram code as in the diagram:
diff --git a/src/diagrams/sequence/parser/sequenceDiagram.jison b/src/diagrams/sequence/parser/sequenceDiagram.jison
index 2669e8606..65a4035f4 100644
--- a/src/diagrams/sequence/parser/sequenceDiagram.jison
+++ b/src/diagrams/sequence/parser/sequenceDiagram.jison
@@ -47,6 +47,9 @@
 "else"                                                          { this.begin('LINE'); return 'else'; }
 "par"                                                           { this.begin('LINE'); return 'par'; }
 "and"                                                           { this.begin('LINE'); return 'and'; }
+"critical"                                                      { this.begin('LINE'); return 'critical'; }
+"option"                                                        { this.begin('LINE'); return 'option'; }
+"break"                                                         { this.begin('LINE'); return 'break'; }
 <LINE>(?:[:]?(?:no)?wrap:)?[^#\n;]*                             { this.popState(); return 'restOfLine'; }
 "end"                                                           return 'end';
 "left of"                                                       return 'left_of';
@@ -172,9 +175,28 @@ statement
 		// End
 		$3.push({type: 'parEnd', signalType: yy.LINETYPE.PAR_END});
 		$$=$3;}
+	| critical restOfLine option_sections end
+	{
+		// critical start
+		$3.unshift({type: 'criticalStart', criticalText:yy.parseMessage($2), signalType: yy.LINETYPE.CRITICAL_START});
+		// Content in critical is already in $3
+		// critical end
+		$3.push({type: 'criticalEnd', signalType: yy.LINETYPE.CRITICAL_END});
+		$$=$3;}
+	| break restOfLine document end
+	{
+		$3.unshift({type: 'breakStart', breakText:yy.parseMessage($2), signalType: yy.LINETYPE.BREAK_START});
+		$3.push({type: 'breakEnd', optText:yy.parseMessage($2), signalType: yy.LINETYPE.BREAK_END});
+		$$=$3;}
   | directive
 	;
 
+option_sections
+	: document
+	| document option restOfLine option_sections
+	{ $$ = $1.concat([{type: 'option', optionText:yy.parseMessage($3), signalType: yy.LINETYPE.CRITICAL_OPTION}, $4]); }
+	;
+
 par_sections
 	: document
 	| document and restOfLine par_sections
diff --git a/src/diagrams/sequence/sequenceDb.js b/src/diagrams/sequence/sequenceDb.js
index e2898b5ba..df20c5751 100644
--- a/src/diagrams/sequence/sequenceDb.js
+++ b/src/diagrams/sequence/sequenceDb.js
@@ -156,8 +156,8 @@ export const parseMessage = function (str) {
       _str.match(/^[:]?wrap:/) !== null
         ? true
         : _str.match(/^[:]?nowrap:/) !== null
-        ? false
-        : undefined,
+          ? false
+          : undefined,
   };
   log.debug('parseMessage:', message);
   return message;
@@ -188,6 +188,11 @@ export const LINETYPE = {
   SOLID_POINT: 24,
   DOTTED_POINT: 25,
   AUTONUMBER: 26,
+  CRITICAL_START: 27,
+  CRITICAL_OPTION: 28,
+  CRITICAL_END: 29,
+  BREAK_START: 30,
+  BREAK_END: 31,
 };
 
 export const ARROWTYPE = {
@@ -429,6 +434,21 @@ export const apply = function (param) {
       case 'parEnd':
         addSignal(undefined, undefined, undefined, param.signalType);
         break;
+      case 'criticalStart':
+        addSignal(undefined, undefined, param.criticalText, param.signalType);
+        break;
+      case 'option':
+        addSignal(undefined, undefined, param.optionText, param.signalType);
+        break;
+      case 'criticalEnd':
+        addSignal(undefined, undefined, undefined, param.signalType);
+        break;
+      case 'breakStart':
+        addSignal(undefined, undefined, param.breakText, param.signalType);
+        break;
+      case 'breakEnd':
+        addSignal(undefined, undefined, undefined, param.signalType);
+        break;
     }
   }
 };
diff --git a/src/diagrams/sequence/sequenceDiagram.spec.js b/src/diagrams/sequence/sequenceDiagram.spec.js
index 9b9b9cfe6..b0e02ceb3 100644
--- a/src/diagrams/sequence/sequenceDiagram.spec.js
+++ b/src/diagrams/sequence/sequenceDiagram.spec.js
@@ -843,6 +843,80 @@ end`;
     expect(messages[7].from).toBe('Bob');
     expect(messages[8].type).toBe(parser.yy.LINETYPE.ALT_END);
   });
+  it('it should handle critical statements without options', function () {
+    const str = `
+sequenceDiagram
+    critical Establish a connection to the DB
+        Service-->DB: connect
+    end`;
+
+    mermaidAPI.parse(str);
+    const actors = parser.yy.getActors();
+
+    expect(actors.Service.description).toBe('Service');
+    expect(actors.DB.description).toBe('DB');
+
+    const messages = parser.yy.getMessages();
+
+    expect(messages.length).toBe(3);
+    expect(messages[0].type).toBe(parser.yy.LINETYPE.CRITICAL_START);
+    expect(messages[1].from).toBe('Service');
+    expect(messages[2].type).toBe(parser.yy.LINETYPE.CRITICAL_END);
+  });
+  it('it should handle critical statements with options', function () {
+    const str = `
+sequenceDiagram
+    critical Establish a connection to the DB
+        Service-->DB: connect
+    option Network timeout
+        Service-->Service: Log error
+    option Credentials rejected
+        Service-->Service: Log different error
+    end`;
+
+    mermaidAPI.parse(str);
+    const actors = parser.yy.getActors();
+
+    expect(actors.Service.description).toBe('Service');
+    expect(actors.DB.description).toBe('DB');
+
+    const messages = parser.yy.getMessages();
+
+    expect(messages.length).toBe(7);
+    expect(messages[0].type).toBe(parser.yy.LINETYPE.CRITICAL_START);
+    expect(messages[1].from).toBe('Service');
+    expect(messages[2].type).toBe(parser.yy.LINETYPE.CRITICAL_OPTION);
+    expect(messages[3].from).toBe('Service');
+    expect(messages[4].type).toBe(parser.yy.LINETYPE.CRITICAL_OPTION);
+    expect(messages[5].from).toBe('Service');
+    expect(messages[6].type).toBe(parser.yy.LINETYPE.CRITICAL_END);
+  });
+  it('it should handle break statements', function () {
+    const str = `
+sequenceDiagram
+    Consumer-->API: Book something
+    API-->BookingService: Start booking process
+    break when the booking process fails
+        API-->Consumer: show failure
+    end
+    API-->BillingService: Start billing process`;
+
+    mermaidAPI.parse(str);
+    const actors = parser.yy.getActors();
+
+    expect(actors.Consumer.description).toBe('Consumer');
+    expect(actors.API.description).toBe('API');
+
+    const messages = parser.yy.getMessages();
+
+    expect(messages.length).toBe(6);
+    expect(messages[0].from).toBe('Consumer');
+    expect(messages[1].from).toBe('API');
+    expect(messages[2].type).toBe(parser.yy.LINETYPE.BREAK_START);
+    expect(messages[3].from).toBe('API');
+    expect(messages[4].type).toBe(parser.yy.LINETYPE.BREAK_END);
+    expect(messages[5].from).toBe('API');
+  });
   it('it should handle par statements a sequenceDiagram', function () {
     const str = `
 sequenceDiagram
diff --git a/src/diagrams/sequence/sequenceRenderer.js b/src/diagrams/sequence/sequenceRenderer.js
index 6421e8d80..0040a18e4 100644
--- a/src/diagrams/sequence/sequenceRenderer.js
+++ b/src/diagrams/sequence/sequenceRenderer.js
@@ -367,21 +367,21 @@ const drawMessage = function (diagram, msgModel, lineStarty) {
         .attr(
           'd',
           'M ' +
-            startx +
-            ',' +
-            lineStarty +
-            ' C ' +
-            (startx + 60) +
-            ',' +
-            (lineStarty - 10) +
-            ' ' +
-            (startx + 60) +
-            ',' +
-            (lineStarty + 30) +
-            ' ' +
-            startx +
-            ',' +
-            (lineStarty + 20)
+          startx +
+          ',' +
+          lineStarty +
+          ' C ' +
+          (startx + 60) +
+          ',' +
+          (lineStarty - 10) +
+          ' ' +
+          (startx + 60) +
+          ',' +
+          (lineStarty + 30) +
+          ' ' +
+          startx +
+          ',' +
+          (lineStarty + 20)
         );
     }
   } else {
@@ -764,6 +764,45 @@ export const draw = function (text, id) {
         if (msg.message.visible) parser.yy.enableSequenceNumbers();
         else parser.yy.disableSequenceNumbers();
         break;
+      case parser.yy.LINETYPE.CRITICAL_START:
+        adjustLoopHeightForWrap(
+          loopWidths,
+          msg,
+          conf.boxMargin,
+          conf.boxMargin + conf.boxTextMargin,
+          (message) => bounds.newLoop(message)
+        );
+        break;
+      case parser.yy.LINETYPE.CRITICAL_OPTION:
+        adjustLoopHeightForWrap(
+          loopWidths,
+          msg,
+          conf.boxMargin + conf.boxTextMargin,
+          conf.boxMargin,
+          (message) => bounds.addSectionToLoop(message)
+        );
+        break;
+      case parser.yy.LINETYPE.CRITICAL_END:
+        loopModel = bounds.endLoop();
+        svgDraw.drawLoop(diagram, loopModel, 'critical', conf);
+        bounds.bumpVerticalPos(loopModel.stopy - bounds.getVerticalPos());
+        bounds.models.addLoop(loopModel);
+        break;
+      case parser.yy.LINETYPE.BREAK_START:
+        adjustLoopHeightForWrap(
+          loopWidths,
+          msg,
+          conf.boxMargin,
+          conf.boxMargin + conf.boxTextMargin,
+          (message) => bounds.newLoop(message)
+        );
+        break;
+      case parser.yy.LINETYPE.BREAK_END:
+        loopModel = bounds.endLoop();
+        svgDraw.drawLoop(diagram, loopModel, 'break', conf);
+        bounds.bumpVerticalPos(loopModel.stopy - bounds.getVerticalPos());
+        bounds.models.addLoop(loopModel);
+        break;
       default:
         try {
           // lastMsg = msg
@@ -848,13 +887,13 @@ export const draw = function (text, id) {
   diagram.attr(
     'viewBox',
     box.startx -
-      conf.diagramMarginX +
-      ' -' +
-      (conf.diagramMarginY + extraVertForTitle) +
-      ' ' +
-      width +
-      ' ' +
-      (height + extraVertForTitle)
+    conf.diagramMarginX +
+    ' -' +
+    (conf.diagramMarginY + extraVertForTitle) +
+    ' ' +
+    width +
+    ' ' +
+    (height + extraVertForTitle)
   );
 
   addSVGAccessibilityFields(parser.yy, diagram, id);
@@ -1056,17 +1095,17 @@ const buildNoteModel = function (msg, actors) {
     noteModel.width = shouldWrap
       ? Math.max(conf.width, textDimensions.width)
       : Math.max(
-          actors[msg.from].width / 2 + actors[msg.to].width / 2,
-          textDimensions.width + 2 * conf.noteMargin
-        );
+        actors[msg.from].width / 2 + actors[msg.to].width / 2,
+        textDimensions.width + 2 * conf.noteMargin
+      );
     noteModel.startx = startx + (actors[msg.from].width + conf.actorMargin) / 2;
   } else if (msg.placement === parser.yy.PLACEMENT.LEFTOF) {
     noteModel.width = shouldWrap
       ? Math.max(conf.width, textDimensions.width + 2 * conf.noteMargin)
       : Math.max(
-          actors[msg.from].width / 2 + actors[msg.to].width / 2,
-          textDimensions.width + 2 * conf.noteMargin
-        );
+        actors[msg.from].width / 2 + actors[msg.to].width / 2,
+        textDimensions.width + 2 * conf.noteMargin
+      );
     noteModel.startx = startx - noteModel.width + (actors[msg.from].width - conf.actorMargin) / 2;
   } else if (msg.to === msg.from) {
     textDimensions = utils.calculateTextDimensions(
@@ -1166,6 +1205,8 @@ const calculateLoopBounds = function (messages, actors) {
       case parser.yy.LINETYPE.ALT_START:
       case parser.yy.LINETYPE.OPT_START:
       case parser.yy.LINETYPE.PAR_START:
+      case parser.yy.LINETYPE.CRITICAL_START:
+      case parser.yy.LINETYPE.BREAK_START:
         stack.push({
           id: msg.id,
           msg: msg.message,
@@ -1176,6 +1217,7 @@ const calculateLoopBounds = function (messages, actors) {
         break;
       case parser.yy.LINETYPE.ALT_ELSE:
       case parser.yy.LINETYPE.PAR_AND:
+      case parser.yy.LINETYPE.CRITICAL_OPTION:
         if (msg.message) {
           current = stack.pop();
           loops[current.id] = current;
@@ -1187,31 +1229,33 @@ const calculateLoopBounds = function (messages, actors) {
       case parser.yy.LINETYPE.ALT_END:
       case parser.yy.LINETYPE.OPT_END:
       case parser.yy.LINETYPE.PAR_END:
+      case parser.yy.LINETYPE.CRITICAL_END:
+      case parser.yy.LINETYPE.BREAK_END:
         current = stack.pop();
         loops[current.id] = current;
         break;
       case parser.yy.LINETYPE.ACTIVE_START:
-        {
-          const actorRect = actors[msg.from ? msg.from.actor : msg.to.actor];
-          const stackedSize = actorActivations(msg.from ? msg.from.actor : msg.to.actor).length;
-          const x =
-            actorRect.x + actorRect.width / 2 + ((stackedSize - 1) * conf.activationWidth) / 2;
-          const toAdd = {
-            startx: x,
-            stopx: x + conf.activationWidth,
-            actor: msg.from.actor,
-            enabled: true,
-          };
-          bounds.activations.push(toAdd);
-        }
+      {
+        const actorRect = actors[msg.from ? msg.from.actor : msg.to.actor];
+        const stackedSize = actorActivations(msg.from ? msg.from.actor : msg.to.actor).length;
+        const x =
+          actorRect.x + actorRect.width / 2 + ((stackedSize - 1) * conf.activationWidth) / 2;
+        const toAdd = {
+          startx: x,
+          stopx: x + conf.activationWidth,
+          actor: msg.from.actor,
+          enabled: true,
+        };
+        bounds.activations.push(toAdd);
+      }
         break;
       case parser.yy.LINETYPE.ACTIVE_END:
-        {
-          const lastActorActivationIdx = bounds.activations
-            .map((a) => a.actor)
-            .lastIndexOf(msg.from.actor);
-          delete bounds.activations.splice(lastActorActivationIdx, 1)[0];
-        }
+      {
+        const lastActorActivationIdx = bounds.activations
+          .map((a) => a.actor)
+          .lastIndexOf(msg.from.actor);
+        delete bounds.activations.splice(lastActorActivationIdx, 1)[0];
+      }
         break;
     }
     const isNote = msg.placement !== undefined;